1. Field of the Invention
The invention is related to a device for modifying the pressure distribution of a ski, particularly such as an alpine ski, along its gliding surface. The invention is also related to an assembly of front and rear alpine ski binding elements, as well as an alpine ski.
2. Discussion of Background and Relevant Information
Skis used for alpine skiing are constituted by relatively long beams on which the skier's boots are retained by front and rear binding elements. The boots and binding elements are located approximately in the median zone of the ski, which is commonly known as the middle sole.
The ski itself possesses a natural arch when at rest, whereby the middle sole is naturally raised with respect to the front end of the ski, or shovel, and the rear end of the ski, or tail. In addition, the ski possesses a flexibility. While skiing, the ski deforms elastically in response to the various biases it is subjected to from the skier, but also from the terrain over which it glides.
The main bias to which the ski is subjected is constituted by the weight of the skier, and by the reaction to which the gliding surface subjects the ski.
The ski is also biased by the binding elements. In fact, it is known that the binding elements pinch the boot longitudinally. To do this, the rear binding element is generally slidably mounted, and it is elastically returned frontwardly by springs which are commonly known as return springs. The reaction to this pinching action is transmitted by the binding elements to the ski. However, this reaction differs in nature depending upon the mode of assembly of the rear binding element to the ski. Indeed, certain rear binding elements are assembled directly to the ski, whereas others are connected to the front binding element by a non-extensible link, such as a metallic blade that extends beneath the boot.
The ski is also influenced by the position of the skier on his or her boots, depending upon whether the skier carries his or her weight towards the front or towards the rear.
It is known that one can modify the behavior of the ski on the snow, especially its ease of turn initiation, its operational quality in turns and in straight lines, by influencing the arch of the ski, or else by playing with the longitudinal pressure distribution of the ski on the snow. By playing with this pressure distribution, it is known that one can render the ski more or less pivotal or more or less guiding, i.e., one can promote its ability to turn easily, and to provide considerable operational stability. For skis currently on the market, pressure distribution of the ski on the snow is determined mainly by the internal structure of the ski and by the assembly mode of the binding elements to the ski, i.e, with or without the connection blade between the front and rear elements. The pressure distribution can also be influenced by the thrust intensity provided to the return spring.
There are devices with attached elements that enable the pressure distribution of the ski on the snow to be modified. As such, European Patent Application No. 183 586 describes a blade of elastic material attached above the ski, between the binding elements and the ski. In the area of its front end and its rear end, this blade has cursors by means of which a portion of the forces to which the ski is subject are transmitted vertically. However, this device has the disadvantage of mediocre performance with a substantial space requirement. It is adapted for the case where both feet of the skier are in support on the same ski, so as to avoid the entire weight of the skier from being concentrated in the middle sole zone. On the contrary, it would be maladapted in the case of a pair of conventional skis.
In European Patent Application No. 409 749 a device is disclosed that is constituted by a plate, raised with respect to the upper surface of the ski, maintained between two longitudinal abutments. Elastic shock absorption means are inserted between the plate and the abutments, and the pre-stress exerted on these elastic means is adjustable. The bindings are mounted on the plate. This device provides good results, but its disadvantage is that the plate is raised with respect to the ski along its entire length. Therefore, it behaves like a stiffener for the ski, and because of this, it disturbs the flexional movements of the ski. In addition, the plate induces an identical pre-stress on the ski towards the front and rear of the middle sole.
It must also be noted that these known devices induce a static-type modification of the pressure distribution on the ski, i.e., this induced modification is not influenced by the position of the skier on his or her skis during the glide.
German Patent Application 41 01 997 describes a ski equipped with a support plate which bears the front and rear binding elements. The support plate is connected to the ski by journals or connecting rods, and a layer of shock absorbing material is inserted between the plate and the ski.
This device enables a free flexion of the ski in the zone of the boot, i.e., it reduces the disturbances that the boot and the binding elements generate on the flexion of the ski. Therefore, this device does not exert any motive or directive action on the flexion of the ski.